. >>> in beijing, air pollution remains off the chart as a toxic fog continues to hang over the china's capital city. schools have canceled outdoor activity, hospitals are getting flooded with patients with breathing problems, and children and the elderly are being warned to stay indoors. the air pollution index has more than doubled what is considered dangerous. it's being blamed on rapid economic growth and a surge in car ownership. >>> on many mass transit subway systems, you never really know what you're going to see. ain't that the truth? particularly here in the big apple. that was definitely the case yesterday as the 12th annual no-pants subway ride took place. >> it's a global event actually, taking place on subways in 60 cities in over 25 countries. here in new york, organizers said more than 4,000 people took part. >> lucky for them, temperatures here yesterday rose into the 50s. so perhaps it wasn't so bad after all. this was all organized by an improv group. we did all these stories about flu and the stuff going on and you're going to put your bare you know what on a subway